A vehicle lift is a device operable to lift a vehicle such as a car, truck, bus, etc. Some vehicle lifts operate by positioning two or more scissor lift assemblies at, or near, a shop floor level. The vehicle may be then driven or rolled into position above the two scissor lift assemblies, while the scissor lift assemblies are in a retracted position. The scissor lift assemblies may be actuated to extend the height of the scissor lift assemblies, thus raising the vehicle to a desired height. Where two scissor lift assemblies are utilized, the scissor lift assemblies may be positioned at a central location relative to the vehicle's body such that the vehicle may balance on the scissor lift assemblies (e.g., under each axle). Afterward, once the user has completed his or her task requiring the vehicle lift, the vehicle may then be lowered. In some instances, the scissor lift assemblies may be equipped with a hydraulic cylinder or other similar device to actuate the scissor lift assemblies. In such instances, actuating two or more hydraulic cylinders with a single hydraulic pump may lead to the pressure of hydraulic fluid in one or more of the hydraulic cylinders to become unbalanced. Such an imbalance of hydraulic fluid may lead to the scissor lift assemblies extending at differing rates, thus forcing the vehicle out of balance as it is raised to the desired height. In other instances, such as where two hydraulic cylinders are used in a single scissor lift assembly or another type of vehicle lift, an imbalance in hydraulic fluid pressure between two hydraulic cylinders may cause certain moving parts of the vehicle lift to bind, wear unevenly, distort, etc. Thus, it may be desirable to balance the pressure of hydraulic fluid delivered to each hydraulic cylinder when multiple hydraulic cylinders are used to actuate the vehicle lift.
Examples of vehicle lift devices and related concepts are disclosed in U.S. Pat. No. 6,983,196, entitled “Electronically Controlled Vehicle Lift and Vehicle Services System,” issued Jan. 3, 2006; U.S. Pat. No. 6,763,916, entitled “Method and Apparatus for Synchronizing a Vehicle Lift,” issued Jul. 20, 2004; U.S. Pat. No. 6,601,430, entitled “Jack with Elevatable Platform,” issued Aug. 5, 2003; U.S. Pat. No. 6,484,554, entitled “Portable Lift and Straightening Platform,” issued Nov. 26, 2002; U.S. Pat. No. 6,269,676, entitled “Portable Lift and Straightening Platform,” issued Aug. 7, 2001; U.S. Pat. No. 6,059,263, entitled “Automotive Alignment Lift,” issued May 9, 2000; U.S. Pat. No. 5,199,686, entitled “Non-Continuous Base Ground Level Automotive Lift System,” issued Apr. 6, 1993; U.S. Pat. No. 5,190,122, entitled “Safety Interlock System,” issued Mar. 2, 1993; U.S. Pat. No. 5,096,159, entitled “Automotive Lift System,” issued Mar. 17, 1992; and U.S. Pub. No. 2012/0048653, entitled “Multi-Link Automotive Alignment Lift,” published Mar. 1, 2012.
While a variety of vehicle lifts have been made and used, it is believed that no one prior to the inventor(s) has made or used an invention as described herein.
The drawings are not intended to be limiting in any way, and it is contemplated that various embodiments of the invention may be carried out in a variety of other ways, including those not necessarily depicted in the drawings. The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention; it being understood, however, that this invention is not limited to the precise arrangements shown.